volte-face
noun [ C usually singular ] literary uk/ˌvɒltˈfæs/ us/ˌvoʊltˈfæs/ volte-face
（信仰等的）大转变，完全转变
a sudden change from one set of beliefs or plan of action to the opposite
In 1986 he made a very public and dramatic political volte-face from Left to Right. 1986年他在政治上公开来了个大转变，从左派变成了右派。
Synonyms: U-turn about-turn (DIRECTION) flip-flop (CHANGE) reversal